diff --git a/lib/squib/commands/make_sprue.rb b/lib/squib/commands/make_sprue.rb
index 6fd69fb..f004cd2 100644
--- a/lib/squib/commands/make_sprue.rb
+++ b/lib/squib/commands/make_sprue.rb
@@ -156,6 +156,8 @@ module Squib
           val_mm = val * 25.4
         elsif from_unit == :cm
           val_mm = val * 10.0
+        else
+          val_mm = val
         end
 
         if to_unit == :in